Principle of Engine Operation

Select the proper order of the four strokes in a small engine

• Compression, Exhaust, Power, Intake

• Intake, Power, Exhaust, Compression

• Intake, Compression, Power, Exhaust

• Compression, Intake, Exhaust, Power

Answer explanation

The correct order of strokes in a small engine is Intake, Compression, Power, Exhaust. This sequence describes how air-fuel mixture enters, is compressed, ignites to produce power, and finally exhausts the gases.

During an intake stroke the _______ moves down and creates a___________

• Piston + Positive Pressure

• Piston + Vacuum

• Flywheel + Spark

• Piston + Explosion

Answer explanation

During an intake stroke, the piston moves down, creating a vacuum in the cylinder. This vacuum allows air and fuel to be drawn into the combustion chamber, making 'Piston + Vacuum' the correct choice.

During an intake stroke the intake valve is _________

• Pressurized

• Inactive

• Closed

• Opened

Answer explanation

During an intake stroke, the intake valve is opened to allow air-fuel mixture into the cylinder. This is essential for the engine's operation, making 'Opened' the correct choice.

During a compression stroke the _______ moves upward and ___________

• Piston + the exhaust valve is opened

• Piston + the intake valve is opened

• Piston + compresses fuel air mixture

• Piston + Both valves are opened

Answer explanation

During the compression stroke, the piston moves upward and compresses the fuel-air mixture, increasing pressure and temperature, which is essential for efficient combustion in the engine.

During a power stroke the piston moves down with_____  ___________

• A Vaccum

• Great Force

• Large Spark

• Valves Opened

Answer explanation

During a power stroke, the piston moves down with great force due to the combustion of fuel, which generates high pressure. This force is essential for converting the energy from combustion into mechanical work.

During a power stroke ____ valves are _______

• Both + Closed

• Both + Opened

• Both + Inactive

• None of the above

Answer explanation

During a power stroke, both the intake and exhaust valves are closed to allow for maximum pressure buildup in the cylinder, which is essential for efficient power generation. Therefore, the correct answer is 'Both + Closed'.

During the exhaust stroke the piston moves______

• Up

• Down

• Sideways

• The Intake vavle

Answer explanation

During the exhaust stroke, the piston moves up to expel exhaust gases from the cylinder. This upward movement is essential for completing the four-stroke cycle, making 'Up' the correct answer.

The intake valve is associated with the _________

• Flywheel

• Muffler

• Carburetor

• Sump

Answer explanation

The intake valve is part of the carburetor system, which mixes air and fuel for combustion. It allows the air-fuel mixture to enter the engine, making 'Carburetor' the correct choice.

Spark occurs between the _____ stroke + the ______ stroke 

• Compression + Power

• Compression + Exhaust

• Power + Exhaust

• Intake + Compression

Answer explanation

Spark occurs between the Compression and Power strokes in an engine cycle. During these strokes, the air-fuel mixture is compressed and ignited, leading to the power generation needed for engine operation.

The exhaust valve is associated with the _________

• Flywheel

• Muffler

• Carburetor

• Sump

Answer explanation

The exhaust valve is associated with the muffler, as it helps release exhaust gases from the engine into the muffler, which then reduces noise and directs the gases away from the vehicle.